The present proposal aims at investigating the hypothesis that age deficits in working-memory-related tasks are due to executive control demands. The working memory model we adopt is Oberauer's (2002) tripartite concentric model, a combination of Cowan's (2001) embedded-process model with McEIree's (2001) focus- of-attention theory. The executive control processes investigated are, first, focus shifting (a process following directly from McEIree's model), and further the four processes identified by Miyake et al. (2001) in a confirmatory factor analysis as basic control processes: task shifting, updating, resistance to interference, and coordination/integration. These five processes will be manipulated both individually and in combination, in a series of experiments involving three tasks: a modified N-Back task, a Continuous Calculation task, and a Repetition Detection task; both accuracy and latency will be measured. For the two former tasks, we will also collect response time distributions, which will be analyzed using ex-Gaussian decomposition. The main questions of the proposal are: 1. With regard to cognitive theory: whether or not the five proposed main executive control functions can be dissociated from each other, using as dissociation tools (a) the selective influence of these processes on distinct parameters of the ex-Gaussian distribution (where applicable); and (b) the selective influence of age on accuracy, reaction time, or distinct parameters of the ex-Gaussian distribution; 2. With regard to cognitive theory: how these five control functions combine (in an additive fashion, with underadditivity, or with overadditivity); examined at the level of (a) log(accuracy), (a) reaction time, and (c) the distinct parameters of the ex-Gaussian distribution; 3. With regard to aging theory: whether or not each of these control functions are age-sensitive with regard to accuracy, reaction time, or distinct parameters of the ex-Gaussian distribution (where applicable), and whether or not the combination of these processes leads to increased age-sensitivity; 4. With regard to aging theory: whether or not the capacity of the zone of direct access of working memory (Cowan, 2001; McEIree, 2001; Oberauer, 2002) changes with age.